DescriptionDiagnosis: Kurixalus idiooticus is a small treefrog similar to K. eiffingeri but with a smaller body size. It has a smaller and weakly developed pollex, has less rugose skin. No female anal flap is present, dorsal warts lack white spinules, its ground color is never greenish, and generally a large dark brown hourglass-like pattern on the back. Males have an aggressive vocal behavior. The species has a generalized larval morphology. In contrast to all other known Taiwanese rhacophorine frogs, K. idiooticus lays eggs terrestrially near the water's edge without constructing a foam nest (Kuramoto and Wang 1987).

Description: SVL ranges from about 24 mm to 43 mm. Females are generally larger than males. Head length is the same as head width. Its snout is short, pointed and triangular, with a rounded, concave canthus rostralis and an oblique, concave loreal region. Eyes are quite protuberant. The Tympanum is distinct and vertically ovoid, with an elevated annulus, and is partially covered on the dorsal side by a well-developed and tuberculated supratympanic fold. The top of the head and upper eyelids are tuberculate. The dorsal surface of the body has elliptical and longitudinal tubercles of varying sizes, as well as granules. Sides of the body are also tuberculate. Belly is coarsely granulated. Forearm, tarsus and fifth toe have white granules on their outer sides. The throat is also finely granulated. Limbs are coarsely granulated on the ventral surface. All fingers have well-developed digital discs which are surrounded by circum-marginal grooves; the disc on finger 3 is as broad as the tympanum. Relative disc sizes of fingers decrease from 3>4>2>1. Relative finger lengths are 3>4>2>1. Fingers have rudimentary webbing. Toe discs are also surrounded by circum-marginal grooves but toe discs are smaller than the discs on fingers 3 and 4. Toes have moderate webbing. Relative toe lengths are 4>5>3>2>1. No tarsal fold is present. The inner metatarsal tubercle is large and elliptical, while the outer metatarsal tubercle is lacking. The tibiotarsal joint bears a distinct, conical, white tubercle. The anal opening has white granules both on the dorsal side and on the ventral side of the opening. Males have a single gular pouch and two vocal slits. The pollex is larger in females than males (Kuramoto and Wang 1987).

Tadpoles are pond-type (rounded body, small mouth and sinistral spiracle with moderate tail). At stages 25-27, body length is 1.4-1.5x longer than wide. Body is oval and moderately depressed. Eyes and nostrils are dorsolateral. Dorsal fin is slightly larger than ventral fin. Caudal musculature is slender and tapers gradually to the tip of the tail. Papillae are marginal, small, and homogeneous in size; they form a continuous row across the ventral lip and extend to the sides of the lips. LTRF is 2:1 +1/3 at stages earlier than 37 and 2:3+3/3 or 1:4+4/3 at stage 37. Head and body are generally dark brown, sometimes with black spotting. Caudal muscle is dark brown. Fins are transparent at stage 25. (Kuramoto and Wang 1987).

Coloration in life: Ground color of light grayish brown, brown, dark brown or yellowish brown (never greenish). The dorsum is characterized by a dark brown stripe. Dark brown spots and patches are on the sides of head. A brown bar extends from the nostril to edge of upper lip, and another brown bar extends from the anterior lower edge of the eye to the edge of the upper lip. The Upper lip has a few narrow dark bars. An inverted Y shape in brown or black extends from a dark cross band between upper eyelids to posterior part of the back. This marking can be Y-shaped, H-shaped or X-shaped, or may be lacking. Sides of the body have dark brown marbling with some dark spots. Anterior throat has dark brown marbling and spotting, as well as some white granules. The belly is dark brown and marbled, scattered with dark spots. Forearms have a dark brown cross band. Thighs have numerous small dark patches on both the anterior and posterior sides. A dark knee patch is present. The sides of the anal opening are dark brown; white granules are present on the dorsal and ventral sides of the anal opening (Kuramoto and Wang 1987).

K. idiootocus is widespread in Taiwan (e.g., PInglin, Mientien-shan, Chutung, Suao, Chushan, Chiahsien, Anping) at altitudes from 10-750 m asl (Kuramoto and Wang 1987). It generally occurs at a lower elevation than the closely related species C. eiffingeri; so far the two species are known to overlap only at Anping (Kuramoto and Wang 1987). Habitat includes grassland, paddy fields and shrublands or anywhere near still, shallow water bodies (Stuart et al. 2008).

Life History, Abundance, Activity, and Special BehaviorsThe breeding season lasts from March-June with males calling from the ground or in low shrubs, often near rain pools (5-20 cm in depth) that are surrounded by high vegetation (grasses or bushes). Males form large breeding aggregations and calling males confront one another, with one male ceasing to call. Calls resemble birds warbling and generally consist of a long series (2-6 seconds) of fast, repeating pulses, but other call types include short trills with sharp pulses and short calls with a long pulse. Males are aggressive and calling males approach each other, with one male then ceasing to call (Kuramoto and Wang 1987).

K. idiootocus lays pigmented eggs (gray-brown animal half, light yellowish gray vegetal half) with transparent gelatinous coats. Ova measured about 1.95 mm in diameter and were covered with two jelly layers, with the diameter of the outermost, tough, non-sticky jelly layer about 4.09 mm. Eggs are laid terrestrially near the water's edge or in depressions, with hatching triggered by rainfall, filling the depressions or washing the tadpoles into adjacent ponds and ditches. Some egg masses were observed more than 50 cm in horizontal distance from the water. Egg masses were often concealed under fallen leaves or other debris, in soil depressions or in crevices behind stones or openings of rat holes. The clutch size averaged 182 eggs. Tadpoles of K. idiooticus have a varied vegetal diet (n contrast to those of K. eiffingeri, which are oophagous) and accelerated their growth later in development than did tadpoles of K. eiffingeri (Kuramoto and Wang 1987).

Trends and ThreatsPopulations are stable with the major threat being habitat destruction and degradation from human settlements. Its range overlaps with many protected areas in Taiwan (Stuart et al. 2008).

Possible reasons for amphibian decline

General habitat alteration and lossHabitat modification from deforestation, or logging related activitiesUrbanization

Comments

Species authority: Kuramoto and Wang (1987).

Karyotype: 2n=26 with eight small pairs and five large pairs of chromosomes (Kuramoto and Wang 1987).

Phylogenetic relationships: K. idiootocus is closely related to K. eiffingeri. and has gone through several taxonomic changes. Kuramoto and Wang (1987) suggested these species might be related to the genus Buergeria.

Etymology: The specific epithet idiootocus is derived from the Greek words “idios,” or peculiar, and "ootocos," or egg-laying (Kuramoto and Wang 1987).